import Util.ListNode;

public class Solution25 {

    public ListNode merge(ListNode list1, ListNode list2){
        ListNode head = new ListNode(-1);
        ListNode cur = head;
        while (list1 != null && list2 != null){
            if (list1.val <= list2.val){
                cur.next = list1;
                list1 = list1.next;
            }
            else {
                cur.next = list2;
                list2 = list2.next;
            }
            cur = cur.next;
        }
        if (list1 != null)
            cur.next = list1;
        if (list2 != null)
            cur.next = list2;
        return head.next;
    }
}
